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Optimax
- Thread starter cupking
- Start date
This is frequently debated BUT I can offer one fact that I have experienced ...
Every morning before I used Optimax the engine seemed VERY lumpy. It actually accelerated fine but whenever my foot came off the accelerator it almost lurched back (almost as if a brake was on)
Anyway, the very next morning after I filled with Optimax, and ever since, this sensation has gone!
I suppose it could be part of the new car process (bedding in, etc.) and just be a coincidence but Ive stuck with it since just in case
Craig
Do a search BenR explained it all a few weeks ago.Quote: Originally posted by Bubba 182 on 30 June 2004
its higher octane (98ron in lieu of 95ron).......it means it burns hotter and produces more power....its easier to ignite and means engines timing can be advanced further.......optimax also has cleaning properties .....hope that helps....
Higher ROn fuel means less knockin so the timing can be adjusted and compression ratio increased so more power.
The 172/182 were designed for 97+ RON plus the extra cleaners in optimtax etc are better for the engine so Id sue them rather than cheapo supermarket stuff.
Astra VXR 17/05/07
Lets sue then
Hippys bus of LOVE !!!
Worth every penny
Hippys bus of LOVE !!!
Lol I promise...
I still cant resist Tesco @ 72.9p a litre http://www.cliosport.net/forum/smileys/smiley9.gif (when you spend £50 on shopping!)...
Does anyone know how the ESSO Super Unleaded shapes up??
Unfortunately where I live I have a choice of a couple of ESSO garages or Tesco, Safeway or Total. The nearest Shell garage is 20 miles so it seems a bit expensive to spend more on fuel to fill up AND use more fuel to get there just to use the Optimax.
COOL BLUE - 106 OCTANE - its like havin a turbo on ya car £45.00 for 10 litres. If ya want some PM me.
Your engine is tunned for a set RON fuel so using higher spec fuel its wasted and possibly you might even loose power.
172/182 are speced for 98 RON fuel using lower stuff means less power using higer spec stuff means no more power and possibly lower power. If your engine is remapped (SMT6 etc) then it can take advantage of higer RON fuel but apart from that its a waste buying fuel of a higer spec than your engine is designed to use.
I want to get a 172 with Avgas mapping (100/130 RON) personally.
[Edited by edde I made a msstake as someone reminded me 182 are 98 RON mapped on 01 July 2004 at 9:33pm]
Optimax wont make any difference to a 1.2 16V as its designed and mapped for lower ron fuel (no idea what spec. 92 Id guess but maybe 95 RON)
You could increase the compression ration of the engine and have it rempped to take advantage of higer ROn fuel but it would be expensive for little gains.
Hmmm I felt Optimax did benefit my old 1.2 16v. Could have been a placebo effect I know but I havent used any other fuel since that first time two and a half years ago....
I am not that clued up on the Clio engine but the engine in my Vectra is not "mapped" for any specific type of fuel as such. It has a knock sensor that adjust the ignition timing in relation to the fuel being used.
Does the 1.2 16v engine have that ability? I thought most modern engines did? In which case it will have just as much of a performance benefit in percentage terms as a 172/182.
Octane actually makes the fuel more difficult to burn, it stablises the fuel meaning that it doesnt ignite before its needed, reducing pinking (pre-ignition). It means the timing can be adjusted more easily, and revs can be raised higher. Lead was used as a cheap alternative to octcane. New Volvos and high performance BMWs need to use high octain fuels...Quote: Originally posted by Bubba 182 on 30 June 2004
its higher octane (98ron in lieu of 95ron).......it means it burns hotter and produces more power....its easier to ignite and means engines timing can be advanced further.......optimax also has cleaning properties .....hope that helps....
There may have been an advantage as the injectors are cleaner so flow fuel better also optimax etc have other bits in the fuel which lead to a cleaner burn.
The Vectra engine and all engines so long as there electronic fuel injection (all modern engines are I think) are mapped and designed for a set fuel the 1.2 is for lower spec than the 172/182 the Vectra is probably tunned for lower spec fuel.
All EFI engine have knock sensors so if lower spec fuel is used or the fuel start to knock then its detected and fueling etc adjusted.
The ability to take advantage of higer RON fuel isnt just based on the engine mapping its also the compresion ratio of the engine and other factors. You can adjust an engine to take advantage in the 1.2 case it would be to increase the compression ratio and remap.
The knock senosor just detects knock and tells the ecu to adjust its settings.
The potential for knock depends on more than just RON of the fuel.
http://forum.cliosport.net/display_topic_threads.asp?ForumID=6&TopicID=92387&SearchPagePosition=1&search=optimax&searchMode=allwords&searchIn=Topic&forum=0&searchSort=dateDESC&ReturnPage=Searchhttp://forum.cliosport.net/display_topic_threads.asp?ForumID=6&TopicID=92387&SearchPagePosition=1&search=optimax&searchMode=allwords&searchIn=Topic&forum=0&searchSort=dateDESC&ReturnPage=Search
172/182 dont benefit that much from optimax, i never used premium fuel in mine that often.
Knock sensors are used as protection, not as the difinative form of ignition control. The engines are setup not to run on a specific fuel, but to run on may different grades and qualities and contain a worst case scenario map. However what they work most efficiently is totally diff.
Doesnt really matter what you use TBH, they arent in a high enough state of tune to kill themselves as a result of octane. AFR yes, fuel no.
Edde, mapping on 100+ octane fuel wont get you anywhere......there is a set limit where the optimal ignition advance is...and going further reduces poewr and increases forces acting on the crank/rods/pistons.
Quote: Originally posted by craig182 on 30 June 2004
This is frequently debated BUT I can offer one fact that I have experienced ...
Every morning before I used Optimax the engine seemed VERY lumpy. It actually accelerated fine but whenever my foot came off the accelerator it almost lurched back (almost as if a brake was on)
Anyway, the very next morning after I filled with Optimax, and ever since, this sensation has gone!
I suppose it could be part of the new car process (bedding in, etc.) and just be a coincidence but Ive stuck with it since just in case
Craig
All 182s do this on all types of fuel they are just crap when they are cold.
I use optimax all the time i get slightly better mpg and better performance but second part could be in my head!
my blokes old supra used to run like a bag of sh*t on tesco unleaded, misfiring and all sorts, wen on optimax it ran like a dream and much quicker! defiantly worth it but then he was spending about 1600grand a month on fuel and £200 a fortnight on new tyres, the silly bugger, that didnt last for long! and with a mpg or aropund 19 to the gallon it was very uneconomical to say the least! good thing it blew up really!
Would there be no advantage to have 100 RON mapping maped up then?
How come the 172/182 owners are told to run on 98+ RON fuel then if to be honest there no real advantage? is it just a thing to make the customer feel like its a high performance car?
I understand what your saying about maping so is there 2 sets of maps one for the wosrse case and the other the one the engine is designed for ie 98 RON in 2.0liter cases? If a 182 is filled with 95 RON fuel and this didnt induce knock then the engine would make the same amount of power than running on 98 RON wouldnt it?
As I said before, my Vectra has three preset settings, one is for something like 91 RON, one of 95 RON and the other for 98 RON. It detects the fuel being used and makes adjustments accordingly - one of those adjustments will be to the timing and you certainly notice the performance improvement when running on Optimax over super market fuel.
If the engine was not making adjustments according to the fuel you would probably see no performance improvement what so ever when using 98 RON over 95 RON.
I am sure the 172/182 engine must be sophisticated enough to do this and so in theory should the 1.2 16v.
If not then that doesnt speak highly of Renault.
[Edited by Toypop on 02 July 2004 at 12:58pm]
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